Gemonhoz development of the pathogen Females lay eggs in the abomasum, which then move along with food masses through the intestines and are thrown out with feces. At optimal temperature and sufficient humidity, a larva is formed in them, which after 14-17 hours is released from the egg membranes. Without leaving the faeces, the larva molts twice and reaches the invasive stage. The period of metamorphosis from the moment of egg release to the formation of an infective larva continues at 26° 31/2 - 4 days. Under the influence of an increase or decrease in temperature, development is accelerated or slowed down.
Haemonchus contortus - hairy nematodes, reddish in color. Their thinned head end is provided with a rudimentary capsule with a chitinized tooth inside. A pair of large cervical papillae is located at a distance of 0.4 - 0.5 mm from the head end. At temperatures above 40°, the embryos die, but reaching the invasive stage; at 35–40°, although invasive larvae mature, they are not very stable.
Sheep become infected by ingesting infective larvae in feed or swill. After two molts in the body of the definitive host, the larvae turn into sexually mature males and females in 2-3 weeks. Gemonhoz. an epizootology. Infection of sheep and goats with hemonchosis can occur in two ways. as a result of eating grass with larvae on it and when drinking from small stagnant reservoirs, that is, mainly on a pasture in the spring-summer and autumn seasons. In sheepfolds, invasion, as a rule, does not occur.
Young animals are most intensively invaded and more difficult to buy atomoxetine pills. In lambs first released to pasture, hemonchosis is clinically manifested in late summer and autumn. Seasonal extensiveness and intensity of hemonchosis invasion is directly dependent on climatic, geographical and economic conditions, as well as on the physiological state of animals.
They severely injure the mucous membrane of the abomasum with their tooth located in the oral capsule. Due to the toxic effect of hemonchus on the animal's body, the function of the nervous system is upset, which entails the regular development of atrophic-degenerative changes in the abomasum and the progressive anemia associated with them. According to 3. F. Sominsky, besides, neurohumoral communications of a digestive tract with the central nervous system are seriously broken. On this basis, the secretory and motor functions of the gastrointestinal tract are perverted, the reaction of the gastric contents becomes neutral and even alkaline, and all this creates conditions for metabolic disorders with a predominance of dissimilatory processes.
In the brain and spinal cord, there is swelling of the membranes and brain substance, increased accumulation of glial cell elements, vacuolization, central or diffuse hydrolysis of nerve cells, and neuronophagy phenomena. In the liver, the parenchyma is atrophied, there is no glycogen. There are phenomena of nephrosis, swelling of the intermuscular connective tissue and degeneration of the muscle fibers of the heart muscle. In the lymph nodes, general lymphoid hyperplasia and catarrh of the marginal and deep sinuses are observed.
It is difficult to make an intravital diagnosis of hemonchosis, since the clinical signs are nonspecific, and the eggs of the parasite are indistinguishable from those of other strongylates. More or less accurately, the disease is recognized according to autopsy data and the presence of a large number of pathogens of hemonchosis.
Gemonchs parasitize in the abomasum of sheep and goats, less often in other ruminants. They feed on blood (hematophagous). Gemonhoz is distributed mainly in the southern regions of the country and in Transbaikalia, where it causes great damage to sheep breeding.
Ruminants become infected by ingestion of invasive haemonch larvae with food or water. For about two weeks, the larvae are in the glands of the abomasum, where they grow, molt, and then exit into the lumen of the abomasum or small intestines and reach the sexually mature stage in 2.5-3 weeks. Gemonchi parasitize ruminants for 6-8 months.
Life cycle. Gemonchs develop without the participation of intermediate hosts. Together with the excrement of ruminants, the eggs of haemonchs are released outside, where in the summer larvae of stage I develop inside them, which leave the egg shells after two days. Then there is a double molt of larvae, after which (on the 5-7th day) they become invasive (stage III). In spring and autumn, the period of development of haemonch larvae to the invasive stage is extended.
Lambs of the current year of birth are more often affected and severely ill with hemonhoz at the end of summer and autumn. The degree of infestation of ruminants decreases in winter. Low-lying, swampy pastures or depressions on dry lands, where water flows, are to a large extent inhabited by larvae. Under conditions of frequent changes in drying and moistening, hemonch larvae can live for 3-4 months.
During the period of parasitism in the abomasum and small intestines, they injure the mucous membrane of these organs with a sharp tooth of the oral capsule. Mechanical damage to the mucous membrane is often accompanied by bleeding and ulceration of the latter.
Hemonchs are hematophagous. In addition, parasites, apparently, release toxins, and are also able to act antigenically and inoculate microbes, resulting in functional disorders of the digestive and nervous systems.
At autopsy of the corpses of ruminants that have died from hemonchosis, a large number of parasites are found in the abomasum, covering the mucous membrane of this organ in the form of dense felt. The content of the abomasum is colored dark red. The mucous membrane of the abomasum and the anterior part of the small intestines is thickened, inflamed and covered with small hemorrhages.
It is very difficult to make a diagnosis during the life of animals, since the eggs of the haemonch do not differ from the eggs of many strongylates. The final diagnosis is established posthumously at autopsy or examination of the carcasses of forcedly killed ruminants and the detection of parasites and characteristic pathological changes in the abomasum.